Iron rusts from disuse, stagnant water loses its purity and in cold weather becomes frozen; even so does inaction sap the vigors of the mind.
A person who doubts himself is like a man who would enlist in the ranks of his enemies and bear arms against himself. He makes his failure certain by himself being the first person to be convinced of it.
Reason is the cause of our falsification of the evidence of the senses. In so far as the senses show becoming, passing away, change, they do not lie.
